Remove multiple indices from array

Question

I have an array and I want to remove a bunch of indices

var arr = [0,1,2,3,4,5,6]
var rmIndices = [1,4,5]

What is the best way to remove indices 1,4,5 from arr?

Answer 1

Note that PermutationGenerator is going away in Swift 3 and also doesn't keep the ordering the same, though perhaps it did at one time. Using the accepted answer results in [2, 6, 0, 3] which may be unexpected. A couple of alternative approaches that give the expected result of [0, 2, 3, 6] are:

let flatArr = arr.enumerate().flatMap { rmIndices.contains($0.0) ? nil : $0.1 }

or

let filterArr = arr.enumerate().filter({ !rmIndices.contains($0.0) }).map { $0.1 }

Answer 2

rmIndices.sort({ $1 < $0 })     

for index in rmIndices
{
    arr.removeAtIndex(index)
}

Note that I've sorted the indices in descending order. This is because everytime you remove an element E, the indices of the elements beyond E reduce by one.